/*
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Valentin V. Bartenev
 */


#ifndef _NGX_HTTP_V2_H_INCLUDED_
#define _NGX_HTTP_V2_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


#define NGX_HTTP_V2_ALPN_ADVERTISE "\x02h2"
#define NGX_HTTP_V2_NPN_ADVERTISE  NGX_HTTP_V2_ALPN_ADVERTISE

#define NGX_HTTP_V2_STATE_BUFFER_SIZE 16

#define NGX_HTTP_V2_DEFAULT_FRAME_SIZE (1 << 14)
#define NGX_HTTP_V2_MAX_FRAME_SIZE     ((1 << 24) - 1)

#define NGX_HTTP_V2_INT_OCTETS 4
#define NGX_HTTP_V2_MAX_FIELD \
    (127 + (1 << (NGX_HTTP_V2_INT_OCTETS - 1) * 7) - 1)

#define NGX_HTTP_V2_STREAM_ID_SIZE 4

#define NGX_HTTP_V2_FRAME_HEADER_SIZE 9

/* frame types */
#define NGX_HTTP_V2_DATA_FRAME          0x0
#define NGX_HTTP_V2_HEADERS_FRAME       0x1
#define NGX_HTTP_V2_PRIORITY_FRAME      0x2
#define NGX_HTTP_V2_RST_STREAM_FRAME    0x3
#define NGX_HTTP_V2_SETTINGS_FRAME      0x4
#define NGX_HTTP_V2_PUSH_PROMISE_FRAME  0x5
#define NGX_HTTP_V2_PING_FRAME          0x6
#define NGX_HTTP_V2_GOAWAY_FRAME        0x7
#define NGX_HTTP_V2_WINDOW_UPDATE_FRAME 0x8
#define NGX_HTTP_V2_CONTINUATION_FRAME  0x9

/* frame flags */
#define NGX_HTTP_V2_NO_FLAG          0x00
#define NGX_HTTP_V2_ACK_FLAG         0x01
#define NGX_HTTP_V2_END_STREAM_FLAG  0x01
#define NGX_HTTP_V2_END_HEADERS_FLAG 0x04
#define NGX_HTTP_V2_PADDED_FLAG      0x08
#define NGX_HTTP_V2_PRIORITY_FLAG    0x20

#define NGX_HTTP_V2_MAX_WINDOW     ((1U << 31) - 1)
#define NGX_HTTP_V2_DEFAULT_WINDOW 65535

#define NGX_HTTP_V2_DEFAULT_WEIGHT 16


typedef struct ngx_http_v2_connection_s ngx_http_v2_connection_t;
typedef struct ngx_http_v2_node_s       ngx_http_v2_node_t;
typedef struct ngx_http_v2_out_frame_s  ngx_http_v2_out_frame_t;


typedef u_char *(*ngx_http_v2_handler_pt)(ngx_http_v2_connection_t *h2c,
                                          u_char *pos, u_char *end);


typedef struct
{
    ngx_str_t name;
    ngx_str_t value;
} ngx_http_v2_header_t;


typedef struct
{
    ngx_uint_t sid;
    size_t     length;
    size_t     padding;
    unsigned   flags : 8;

    unsigned incomplete : 1;
    unsigned keep_pool  : 1;

    /* HPACK */
    unsigned             parse_name  : 1;
    unsigned             parse_value : 1;
    unsigned             index       : 1;
    ngx_http_v2_header_t header;
    size_t               header_limit;
    u_char               field_state;
    u_char              *field_start;
    u_char              *field_end;
    size_t               field_rest;
    ngx_pool_t          *pool;

    ngx_http_v2_stream_t *stream;

    u_char                 buffer[NGX_HTTP_V2_STATE_BUFFER_SIZE];
    size_t                 buffer_used;
    ngx_http_v2_handler_pt handler;
} ngx_http_v2_state_t;


typedef struct
{
    ngx_http_v2_header_t **entries;

    ngx_uint_t added;
    ngx_uint_t deleted;
    ngx_uint_t reused;
    ngx_uint_t allocated;

    size_t  size;
    size_t  free;
    u_char *storage;
    u_char *pos;
} ngx_http_v2_hpack_t;


struct ngx_http_v2_connection_s
{
    ngx_connection_t      *connection;
    ngx_http_connection_t *http_connection;

    off_t total_bytes;
    off_t payload_bytes;

    ngx_uint_t processing;
    ngx_uint_t frames;
    ngx_uint_t idle;
    ngx_uint_t priority_limit;

    ngx_uint_t pushing;
    ngx_uint_t concurrent_pushes;

    size_t send_window;
    size_t recv_window;
    size_t init_window;

    size_t frame_size;

    ngx_queue_t waiting;

    ngx_http_v2_state_t state;

    ngx_http_v2_hpack_t hpack;

    ngx_pool_t *pool;

    ngx_http_v2_out_frame_t *free_frames;
    ngx_connection_t        *free_fake_connections;

    ngx_http_v2_node_t **streams_index;

    ngx_http_v2_out_frame_t *last_out;

    ngx_queue_t dependencies;
    ngx_queue_t closed;

    ngx_uint_t last_sid;
    ngx_uint_t last_push;

    unsigned closed_nodes  : 8;
    unsigned settings_ack  : 1;
    unsigned table_update  : 1;
    unsigned blocked       : 1;
    unsigned goaway        : 1;
    unsigned push_disabled : 1;
};


struct ngx_http_v2_node_s
{
    ngx_uint_t            id;
    ngx_http_v2_node_t   *index;
    ngx_http_v2_node_t   *parent;
    ngx_queue_t           queue;
    ngx_queue_t           children;
    ngx_queue_t           reuse;
    ngx_uint_t            rank;
    ngx_uint_t            weight;
    double                rel_weight;
    ngx_http_v2_stream_t *stream;
};


struct ngx_http_v2_stream_s
{
    ngx_http_request_t       *request;
    ngx_http_v2_connection_t *connection;
    ngx_http_v2_node_t       *node;

    ngx_uint_t queued;

    /*
     * A change to SETTINGS_INITIAL_WINDOW_SIZE could cause the
     * send_window to become negative, hence it's signed.
     */
    ssize_t send_window;
    size_t  recv_window;

    ngx_buf_t *preread;

    ngx_uint_t frames;

    ngx_http_v2_out_frame_t *free_frames;
    ngx_chain_t             *free_frame_headers;
    ngx_chain_t             *free_bufs;

    ngx_queue_t queue;

    ngx_array_t *cookies;

    ngx_pool_t *pool;

    unsigned waiting         : 1;
    unsigned blocked         : 1;
    unsigned exhausted       : 1;
    unsigned in_closed       : 1;
    unsigned out_closed      : 1;
    unsigned rst_sent        : 1;
    unsigned no_flow_control : 1;
    unsigned skip_data       : 1;
};


struct ngx_http_v2_out_frame_s
{
    ngx_http_v2_out_frame_t *next;
    ngx_chain_t             *first;
    ngx_chain_t             *last;
    ngx_int_t (*handler)(ngx_http_v2_connection_t *h2c,
                         ngx_http_v2_out_frame_t  *frame);

    ngx_http_v2_stream_t *stream;
    size_t                length;

    unsigned blocked : 1;
    unsigned fin     : 1;
};


static ngx_inline void
ngx_http_v2_queue_frame(ngx_http_v2_connection_t *h2c,
                        ngx_http_v2_out_frame_t  *frame)
{
    ngx_http_v2_out_frame_t **out;

    for (out = &h2c->last_out; *out; out = &(*out)->next)
    {
        if ((*out)->blocked || (*out)->stream == NULL)
        {
            break;
        }

        if ((*out)->stream->node->rank < frame->stream->node->rank
            || ((*out)->stream->node->rank == frame->stream->node->rank
                && (*out)->stream->node->rel_weight
                       >= frame->stream->node->rel_weight))
        {
            break;
        }
    }

    frame->next = *out;
    *out        = frame;
}


static ngx_inline void
ngx_http_v2_queue_blocked_frame(ngx_http_v2_connection_t *h2c,
                                ngx_http_v2_out_frame_t  *frame)
{
    ngx_http_v2_out_frame_t **out;

    for (out = &h2c->last_out; *out; out = &(*out)->next)
    {
        if ((*out)->blocked || (*out)->stream == NULL)
        {
            break;
        }
    }

    frame->next = *out;
    *out        = frame;
}


static ngx_inline void
ngx_http_v2_queue_ordered_frame(ngx_http_v2_connection_t *h2c,
                                ngx_http_v2_out_frame_t  *frame)
{
    frame->next   = h2c->last_out;
    h2c->last_out = frame;
}


void ngx_http_v2_init(ngx_event_t *rev);

ngx_int_t ngx_http_v2_read_request_body(ngx_http_request_t *r);
ngx_int_t ngx_http_v2_read_unbuffered_request_body(ngx_http_request_t *r);

ngx_http_v2_stream_t *ngx_http_v2_push_stream(ngx_http_v2_stream_t *parent,
                                              ngx_str_t            *path);

void ngx_http_v2_close_stream(ngx_http_v2_stream_t *stream, ngx_int_t rc);

ngx_int_t ngx_http_v2_send_output_queue(ngx_http_v2_connection_t *h2c);


ngx_str_t *ngx_http_v2_get_static_name(ngx_uint_t index);
ngx_str_t *ngx_http_v2_get_static_value(ngx_uint_t index);

ngx_int_t ngx_http_v2_get_indexed_header(ngx_http_v2_connection_t *h2c,
                                         ngx_uint_t                index,
                                         ngx_uint_t                name_only);
ngx_int_t ngx_http_v2_add_header(ngx_http_v2_connection_t *h2c,
                                 ngx_http_v2_header_t     *header);
ngx_int_t ngx_http_v2_table_size(ngx_http_v2_connection_t *h2c, size_t size);


ngx_int_t ngx_http_v2_huff_decode(u_char *state, u_char *src, size_t len,
                                  u_char **dst, ngx_uint_t last,
                                  ngx_log_t *log);
size_t    ngx_http_v2_huff_encode(u_char *src, size_t len, u_char *dst,
                                  ngx_uint_t lower);


#define ngx_http_v2_prefix(bits) ((1 << (bits)) - 1)


#if (NGX_HAVE_NONALIGNED)

#define ngx_http_v2_parse_uint16(p) ntohs(*(uint16_t *)(p))
#define ngx_http_v2_parse_uint32(p) ntohl(*(uint32_t *)(p))

#else

#define ngx_http_v2_parse_uint16(p) ((p)[0] << 8 | (p)[1])
#define ngx_http_v2_parse_uint32(p) \
    ((uint32_t)(p)[0] << 24 | (p)[1] << 16 | (p)[2] << 8 | (p)[3])

#endif

#define ngx_http_v2_parse_length(p) ((p) >> 8)
#define ngx_http_v2_parse_type(p)   ((p)&0xff)
#define ngx_http_v2_parse_sid(p)    (ngx_http_v2_parse_uint32(p) & 0x7fffffff)
#define ngx_http_v2_parse_window(p) (ngx_http_v2_parse_uint32(p) & 0x7fffffff)


#define ngx_http_v2_write_uint16_aligned(p, s) \
    (*(uint16_t *)(p) = htons((uint16_t)(s)), (p) + sizeof(uint16_t))
#define ngx_http_v2_write_uint32_aligned(p, s) \
    (*(uint32_t *)(p) = htonl((uint32_t)(s)), (p) + sizeof(uint32_t))

#if (NGX_HAVE_NONALIGNED)

#define ngx_http_v2_write_uint16 ngx_http_v2_write_uint16_aligned
#define ngx_http_v2_write_uint32 ngx_http_v2_write_uint32_aligned

#else

#define ngx_http_v2_write_uint16(p, s) \
    ((p)[0] = (u_char)((s) >> 8), (p)[1] = (u_char)(s), (p) + sizeof(uint16_t))

#define ngx_http_v2_write_uint32(p, s)                           \
    ((p)[0] = (u_char)((s) >> 24), (p)[1] = (u_char)((s) >> 16), \
     (p)[2] = (u_char)((s) >> 8), (p)[3] = (u_char)(s),          \
     (p) + sizeof(uint32_t))

#endif

#define ngx_http_v2_write_len_and_type(p, l, t) \
    ngx_http_v2_write_uint32_aligned(p, (l) << 8 | (t))

#define ngx_http_v2_write_sid ngx_http_v2_write_uint32


#define ngx_http_v2_indexed(i)     (128 + (i))
#define ngx_http_v2_inc_indexed(i) (64 + (i))

#define ngx_http_v2_write_name(dst, src, len, tmp) \
    ngx_http_v2_string_encode(dst, src, len, tmp, 1)
#define ngx_http_v2_write_value(dst, src, len, tmp) \
    ngx_http_v2_string_encode(dst, src, len, tmp, 0)

#define NGX_HTTP_V2_ENCODE_RAW  0
#define NGX_HTTP_V2_ENCODE_HUFF 0x80

#define NGX_HTTP_V2_AUTHORITY_INDEX 1

#define NGX_HTTP_V2_METHOD_INDEX      2
#define NGX_HTTP_V2_METHOD_GET_INDEX  2
#define NGX_HTTP_V2_METHOD_POST_INDEX 3

#define NGX_HTTP_V2_PATH_INDEX      4
#define NGX_HTTP_V2_PATH_ROOT_INDEX 4

#define NGX_HTTP_V2_SCHEME_HTTP_INDEX  6
#define NGX_HTTP_V2_SCHEME_HTTPS_INDEX 7

#define NGX_HTTP_V2_STATUS_INDEX     8
#define NGX_HTTP_V2_STATUS_200_INDEX 8
#define NGX_HTTP_V2_STATUS_204_INDEX 9
#define NGX_HTTP_V2_STATUS_206_INDEX 10
#define NGX_HTTP_V2_STATUS_304_INDEX 11
#define NGX_HTTP_V2_STATUS_400_INDEX 12
#define NGX_HTTP_V2_STATUS_404_INDEX 13
#define NGX_HTTP_V2_STATUS_500_INDEX 14

#define NGX_HTTP_V2_ACCEPT_ENCODING_INDEX 16
#define NGX_HTTP_V2_ACCEPT_LANGUAGE_INDEX 17
#define NGX_HTTP_V2_CONTENT_LENGTH_INDEX  28
#define NGX_HTTP_V2_CONTENT_TYPE_INDEX    31
#define NGX_HTTP_V2_DATE_INDEX            33
#define NGX_HTTP_V2_LAST_MODIFIED_INDEX   44
#define NGX_HTTP_V2_LOCATION_INDEX        46
#define NGX_HTTP_V2_SERVER_INDEX          54
#define NGX_HTTP_V2_USER_AGENT_INDEX      58
#define NGX_HTTP_V2_VARY_INDEX            59


u_char *ngx_http_v2_string_encode(u_char *dst, u_char *src, size_t len,
                                  u_char *tmp, ngx_uint_t lower);


#endif /* _NGX_HTTP_V2_H_INCLUDED_ */
